While everyone in the area was moved to higher ground, there were fears the water would return as a tsunami.
However a source told nzherald.co.nz some locals believed the island had in fact been pushed up by the earthquake.
He said the interisland ferry could reportedly no longer dock at Salelologa and was moored off-shore.
The man, who has family in the Samoan village of Malaela, on Upolu told nzherald.co.nz his cousin's neighbours had been killed in the tsunami.
"In our village of Malaela there have been fatalities - I was told at least 7-8 bodies recovered, and a number of people missing, including children," he said.
Other villages reportedly with many deaths include Vailoa and Aleipata - one of the worst hit villages.
The owner of Apia's Iliili Resort, Daniela Brussani, says she and her business partner fled by car to a hill, where they watched the destruction on Upolu take place.
"I look at the back, saw the big wave arrive - a big wave - six of seven metres."
Ms Brussani says her resort is now under two metres of water.
Another resort owner, Mataio, says the sea disappeared before his eyes.
He said after the earthquake hit this morning he sat down and had a smoke but then had only five minutes to pack a bag and run for safety.
Mataio said he if he did not have a car, he would not be alive now.
Mike Reynolds, superintendent of the National Park of American Samoa, was quoted as saying four tsunami waves 15 to 20 feet (4 1/2 to 6 metres) high roared ashore soon afterwards, reaching up to a mile (1.6 kilometres) inland.
Holly Bundock, spokeswoman for the National Park Service's Pacific West Region in Oakland, California, said Reynolds spoke to officials from under a coconut tree uphill from Pago Pago Harbour and reported that the park's visitor centre and offices appeared to have been destroyed.
Bundock said Reynolds and another park service staffer had been able to locate only a fifth of the park's 13 to 15 employees and 30 to 50 volunteers.
The National Park of American Samoa is the only national park south of the equator, a scenic expanse of reefs, picturesque beaches, tropical forests and wildlife that include sea turtles and flying foxes, a type of fruit bat.
Residents in both Samoa and American Samoa reported being shaken awake by the quake, which lasted two to three minutes.
The Pacific Tsunami Warning Center issued a general alert from American Samoa to New Zealand; Tonga suffered some coastal damage from 4-metre-high waves.
Mase Akapo, a meteorologist for the National Weather Service in American Samoa, said at least 14 people were killed in four different villages on the main island of Tutuila, while 20 people died neighbouring Samoa.
The initial quake was followed by at three aftershocks of at least 5.6 magnitude.
An Associated Press reporter saw the bodies of about 20 victims in a hospital at Lalomanu town on the south coast of the main island, Upolu, and said the surrounding tourist coast had been flattened, with the dead including those who hesitated to leave right after the quake.
An unspecified number of fatalities and injuries were reported in the Samoan village of Talamoa.
New Zealander Graeme Ansell said the beach village of Sau Sau Beach Fale was levelled.
"It was very quick. The whole village has been wiped out," Ansell told National Radio from a hill near Samoa's capital, Apia.
"There's not a building standing. We've all clambered up hills, and one of our party has a broken leg. There will be people in a great lot of need 'round here."
The Samoan capital was virtually deserted with schools and businesses closed.
Local media said they had reports of some landslides in the Solosolo region of the main Samoan island of Upolu and damage to plantations in the countryside outside Apia.
American Samoa Governor Togiola Tulafono was at his Honolulu office assessing the situation but was having difficulty getting information, said Filipp Ilaoa, deputy director of the office.
Rescue workers found a scene of destruction and debris with cars overturned or stuck in mud, and rockslides hit some roads. Several students were seen ransacking a gas station/convenience store.
Rear Admiral Manson Brown, Coast Guard commander for the Pacific region, said the Coast Guard is in the early stages of assessing what resources to send to American Samoa.
Coast Guard spokesman Lieutenant John Titchen said a C-130 was being dispatched to deliver aid, assess damage and take the governor back home.
A New Zealand air force P3 Orion maritime search aeroplane is also was being sent.
One of the runways at Pago Pago International Airport was being cleared of widespread debris for emergency use, Federal Aviation Administration spokesman Ian Gregor said in Los Angeles.
The Federal Emergency Management Agency said it was deploying teams to American Samoa to provide support and on the ground assessment.
"Our thoughts and prayers go out to the people of American Samoa and all those in the region who have been affected by these natural disasters," Interior Secretary Ken Salazar said.
A number of Australians have been injured in the aftermath of this morning's earthquake and tsunami, the Federal Government said.
"The early reports don't suggest that any of them are very serious, but they are in hospital," parliamentary secretary for international development assistance Bob McMullan told Sky News.
Australian consular officials in Samoa were at local hospitals to offer assistance, he said.
The ramifications of the tsunami could be felt thousands of miles away, with federal officials saying strong currents and dangerous waves were forecast from California to Washington state. No major flooding was expected, however.
The earthquake and tsunami were big, but not on the same large scale of the 2004 Indonesian tsunami that killed more than 150,000 across Asia the day after Christmas in 2004, said tsunami expert Brian Atwater of the US Geological Survey in Seattle.
The 2004 earthquake was at least 10 times stronger than the 8.0 to 8.3 measurements being reported for Tuesday's quake, Atwater said. It's also a different style of earthquake than the one that hit in 2004.
The tsunami hit American Samoa about 25 minutes after the quake, which is similar to the travel time in 2004, Atwater said.
The big difference is there were more people in Indonesia at risk than in Samoa.
- AP, NZ HERALD STAFF, NZPA, AAP
* MFAT says New Zealanders concerned about family members in Samoa should try to make contact with them in the first instance. Those with ongoing concerns could call the Ministry of Foreign Affairs and Trade on 04 439 8000, with as many contact details as possible.
Click here to donate to the Red Cross' Samoa earthquake/tsunami appeal.
